Your absolute best source for this would actually be your hotel concierge. "Membership" restaurants in Japan usually have 'membership' because they are very small and want to make sure their regulars always have a spot; its actually rarely about being elite or status. Another person, even Japanese, would not be able to get reservation for you if they do not have a relationship with owner of the restaurant. I've been to a couple of 'membership' restaurants. One was a small soba shop that did not even take reservation and I was taken there by a friend who was a regular; we made sure to finish our lunch within 15 minutes as that was the unspoken rule. The other time was to a sushi place and the hotel concierge had a good relationship with owner and essentially "guaranteed" my ability to speak Japanese (so I can order from menu and understand chef), and promised my good behavior. So get to know your concierge and see if they can help. But there is so much good food in Tokyo from owners that welcome a new face or a foreign visitor that I don't think it is needed to go to a membership restaurant. The sushi thing was for a blog a friend wanted write and I found the experience less enjoyable then my usual neighborhood sushi joint that welcomed everyone who walked in and did not mind some 'Japenglish'. It was stressful to be on best Japanese behavior for 1.5 hours when I'm not even Japanese.